<!DOCTYPE html>
<html lang="ch-cn">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <link rel="stylesheet" href="./base.css" />
  </head>
  <body>
    <script>
      function foo(x) {
        let num = 5;
        bar = function (y) {
          return x + y + ++num;
          
        };
        // x = null;
      }
      alert(foo(2));
      alert(bar(10));
      alert(bar(10));
    </script>
  </body>
</html>
